The preparation of alkylated urea or melamine formaldehyde resins is well known in the art. Thus, these resins are produced by reacting the urea or melamine with the formaldehyde under neutral or alkaline conditions to form the methylol derivatives followed by alkylation (i.e., etherification) with the alcohol under acidic conditions. As is well known, these are condensation reactions which are attended by the evolution of significant amounts of water. Since the reactions are reversible, it is necessary to remove the water from the reaction zone as it is formed if a reasonable degree of completion of the reaction is to be attained. This is accomplished by well known azeotropic distillation procedure, that is, the reaction mixture is heated to reflux and the water removed azeotropically. In conventional commercial practice, the mixture of alcohol and water vapors produced during the reaction are passed out of the reaction zone to a condenser which produces a liquid condensate consisting of an alcohol rich phase and a water rich phase, following which the alcohol rich and water rich phases are separated in known manner with the alcohol rich phase being returned to the reaction zone and the water rich phase being removed to drainage or to storage for additional processing or use if desired. However, one major problem with such conventional commercial processes has been the lengthy production times involved in producing the resins. We have found that the lengthy reaction times involved in producing these resins by present commercial processes is principally related to the water content of the alcohol being returned to the reaction zone. Thus, due to the solubility of water in alcohol, for example, water is soluble in n-butanol to the extent of 20 percent at 25.degree. C., the alcohol being returned to the reaction zone in percent processes is "wet", i.e., it contains a significant quantity of water. The water in this returning wet alcohol causes a significant depression in the reaction rate. In fact, we have found a significant relationship between the overall reaction times and the water content of the alcohol returning to the reaction zone. For example, we have found that when the water content of the returning alcohol ranges from 16 to 20 percent as is typical in present commercial processes, the reaction time ranges from about 6 to about 18 hours whereas when the water content of the returning alcohol is reduced to 1 percent or less the reaction time is cut in most cases as much as 50 percent and in some instances up to 70 percent.
In accordance with the present invention, we have discovered an apparatus system which is capable of returning substantially dry alcohol (i.e., water content 1 percent or less) to the reaction zone, thereby attaining a reduction in reaction time of 50 percent or more.